1. Field of the Invention
The present invention relates to a gelling agent for an oil. More specifically, the present invention relates to a gelling agent for an oil which contains a particular class of an amino acid derivative. The gelling agent of the present invention is useful for gelling an oil in a state of a liquid at an ordinary temperature to obtain variety forms of the oil.
2. Related Art
As gelling agents for an oil that is insoluble in water, for example, polyamide resins, 12-hydroxystearic acid, condensates of an aromatic aldehyde and a polyhydric alcohol whose typical example includes dibenzylidene-D-sorbitol and the like have been known so far. However, these gelling agents have a problem of low solubility in oils. For example, gel compositions prepared by using these gelling agents have a problem of poor stability in a dissolved state, which results in formation of heterogeneous gel compositions or so-called “sweating phenomenon” as exudation of the gelled oils form the surfaces of the gels due to degradation with time.
As another gelling agent for an oil, N-lauroyl-L-glutamic acid dibutylamide disclosed in Japanese Patent Unexamined Publication (Kokai) No. 51-19139/1976 is known, and cosmetics containing said substance as a gelling agent have been reported. The aforementioned gelling agent can form gels from variety of types of oils. However, gel compositions obtained sometimes fail to have sufficient gel strength. As a result, when gel compositions are prepared as cosmetics for dermal application, the compositions may sometimes become tender and have a problem from a viewpoint of strength.
Furthermore, U.S. Pat. No. 5,591,424 and International Patent Publication in Japanese (Kohyo) No. 7-506833 disclose antiperspirant gel sticks containing 12-hydroxystearic acid and N-lauroylglutamic acid dibutylamide. However, the aforementioned gel sticks are also insufficient in strength, and the sticks may sometimes have difficulty in application to the skin. Moreover, appearance of each gel composition obtained by using the gelling agent and an oil is white and lacks transparency, which is not desired from an esthetic viewpoint.